The bioartificial liver (BAL) has been proposed to carry out liver function during hepatic failure until the native liver has regenerated, or until transplantation is possible. For patients with chronic liver diseases, BAL could perform periodic detoxifications. The ideal BAL would mimic normal liver function. The employment of hollow fiber (HF) membranes for integral oxygenation greatly enhances hepatocyte viability and function. However, although microporous HF membranes have adequate initial performance, after a short period of time, "wet out" and fouling cause gas transport to drop significantly. The applicant scientists propose to fabricate a dual fiber bioreactor utilizing a new, highly efficient gas transfer membrane. This new oxygenation method will provide a longer term, bubbleless oxygen source with increased overall gas flux in order to enhance cell viability and function. The second set fibers will be designed for extraluminal hepatocyte attachment. Successful completion of the proposed R & D effort will produce an enhanced BAL with the ability to provide longer term, significantly improved liver function. PROPOSED COMMERCIAL APPLICATION: Bioarficial livers that provide long term hepatocyte function are expected to provide simple supportive care and serve as a bridge to transplant, or more importantly, improve the health of patients with acute liver failure, and thus avoid a transplant altogether. Our membrane technology will substantially improve oxygen transfer capability within the bioartificial liver and, therefore, significantly improve the performance of such devices.